docs: def start(self):
          """
          Starts the worker threads if they are not already started.
          This method is thread-safe and will be called automatically
          when executing an operation.
          """
          # Check whether we are already started, skip if we are.
          if not self._started.is_set():
              # If we are not started, try to capture the lock.
              if self._lock.acquire(False):
                  # If we got the lock, go ahead and start the worker
                  # threads, set the started flag, and release the lock.
                  for i in range(self._size):
                      name = "riak.client.multi-worker-{0}-{1}".format(
                              self._name, i)
                      worker = Thread(target=self._worker_method, name=name)
                      worker.daemon = False
                      worker.start()
                      self._workers.append(worker)
                  self._started.set()
                  self._lock.release()
              else:
                  # We didn't get the lock, so someone else is already
                  # starting the worker threads. Wait until they have
                  # signaled that the threads are started.
                  self._started.wait()